diff --git a/tools/releasetools/testdata/payload_signer.sh b/tools/releasetools/testdata/payload_signer.sh
new file mode 100755
index 0000000..a44ef34
--- /dev/null
+++ b/tools/releasetools/testdata/payload_signer.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+
+# The script will be called with 'payload_signer.sh <key> -in <input> -out <output>'.
+openssl pkeyutl -sign -keyform DER -inkey $1 -pkeyopt digest:sha256 -in $3 -out $5